I am looking for solutions for longer term digital/physical storage for my BTC, and alt-coins of assorted types. I have been holding onto my coins and watching them steadily increase in value, and I plan on keeping them longer term well into the future. Some of the richest BTC investors today are people who bought coins in 2010/2009 and just forgot all about them until 2013 or now.

They are a great investment so far, and although I have bought and sold in the past as an early adopter of ASIC mining in 2013, I haven't moved/mined any since 2015.... and I first owned BTC at about $60.00 a coin.

One additional issue is that I want my coins to be accessible in case something happens to me, to allow access to them by the caretakers of what is left of my estate. I am considering holding in a safety deposit box at a bank.

The challenge with any storage medium is leaving instructions in how to deal with them to less technically capable persons, particularly those who don't necessarily understand bitcoin/alternate coins, and/or the value. Easy access is important.

For BTC I was considering a Trezor, although I am open to other mediums.

For Dash/LiteCoin/Doge/Cloak/a bunch of other alt coins of varying value - I am open to any suggestions.

One issue that I want to ensure that doesn't happen is the MultiBit HD unconfirmed bug, which I just got over with. It was ass-pain, and while a simple solution, might be beyond the capabilities of others who might have to handle the coins.

Many (somewhat early adopters) have your concerns. I submit that a hardware wallet as you mentioned was being considered, is a super choice. You can always backup the seed and any passwords, PIN, etc.... but in reality a non-techie only needs to know the PIN and any passwords and they are good to go! Plus the added bonus is that if a newbie uses the Trezor you mentioned on an infected computer your coins still cannot be stolen by that malware. If your non-techie heir spends just about 15 minutes reading about how to use a Trezor the coins will be safe. I could easily teach a 12 year old how to safely spend coins on a hardware wallet. Yet, nobody has ever knowingly broken into a hardware wallet using malware.

Due to the rise in Dash, I might be justified in getting one for an alt coin or two if they become available.

I was considering a Raspberry Pi, but I don't know if I trust my coins on a SD Card...... although I could do Wallet backups and keep a second stick in the box.

Paper copies of the wallet words is also important.

Trezor is accepting orders, but I think I will wait a little before ordering. While I have no reason whatsoever to think that the company selling Trezor a similar company to Butterfly Labs, pre-orders in the BTC world still have abit of a reputation to get over!